AMD announced plans to introduce a desktop PC processor with three cores in the first quarter of 2008. The three-core chip will carry the same Phenom brand name that AMD plans to attach to its quad-core desktop chips due to ship to PC companies by the end of this year.

It really might make more sense to design a 5 way core and just assume that the majority of dies have 1 dead core and ship 4 way that way. It complicates things if there is an asymmetry in the design that penalizes some combinations of faults. Now if all 5 worked, I'd still turn one off!